1. Field of the Invention
The present invention relates generally to an apparatus for manufacturing wax dots and, more particularly, to an apparatus that efficiently manufactures wax dots.
2. Description of the Related Art
Plastic items, such as clips, message hooks or label holders, require a mounting surface for packaging and shipping to consumers. As is known to one of ordinary skill in the art, plastic clips may be mounted upon wax dots. These wax dots in turn are typically mounted to a packaging sheet or web material. The wax dots provide a raised surface allowing easy placement and removal of the plastic clip. The adhesive character of the wax dots hold the plastic clips to the packaging web. Additionally, when the clips are removed from the wax dots, substantially no adhesive residue remains on the plastic clips.
A wax dot machine 10 illustrated in FIG. 1 has been used in the art to produce wax dots 12 on a packaging web 14. The wax dot machine 10 forms a row of five wax dots 12 on the web 14. The web 14 is typically a semi-rigid plastic sheet. Each wax dot 12 is a cylinder with a diameter of approximately 3/8 inch and a height of approximately 1/4 inch. When plastic clips are placed onto the wax dots 12, the clips (not shown) adhere to the wax dot 12 until consumers remove them from the wax dots 12.
The wax dot machine 10 continuously produces rows of five wax dots 12 onto the web 14. The web 14 moves in the direction of the arrow A at a constant speed providing approximately equal spacing between adjacent rows of wax dots 12. The web 14 unrolls from a roll of packaging web (not shown) and passes between a pull roller 16 (see FIG. 3) and the wax dot machine 10.
The wax dot machine 10 comprises a wax feeder 20 and a wax dot former 22. The wax feeder 20 comprises a housing 24 enclosing a wax channel 26. The housing 24 comprises two halves 25 that joined together. FIGS. 2 and 3 illustrate the wax channel 26. The wax dot former 22 comprises a housing 28 and a drum 30. A connecting plate 32 connects the housing 24 of the wax feeder 20 to the housing 28 of the wax dot former 22. The wax channel 26 travels through the housing 24 of the wax feeder 20 and divides into five portions which pass through the connecting plate 32 and the housing 28 of the wax dot former 22 to five bores 34 in a block 36. The housings 24 and 28, drum 30, connecting plate 32, and block 36 are composed of steel.
The wax feeder 20 communicates a wax from a wax supply (not shown) through the wax channel 26 to the bores 34. Briefly, a wax plunger (not shown) with a cross-section substantially matching the cross-section of the wax channel 26 moves toward the wax former 22 forcing the wax within the wax channel 26 toward the bores 34. Because the wax is flowable under pressure at room temperature, the pressure provided by the wax plunger moving toward the wax former 22 forces the wax through the bores 34. When the wax plunger retracts, additional wax enters the wax channel 26 from the wax supply.
The wax dot former 22 of the wax dot machine 10 comprises the drum 30 within the housing 28. The drum 30 has twenty rows of five holes 38. The holes 38 have a diameter of approximately 3/8 inch. When the holes 38 are aligned with the bores 34, the holes 38 have a depth of approximately 1/4 inch, and each hole 38 receives wax from the wax feeder 20. The wax passes through the bores 34 and fills the holes 38 forming the wax dots 12. In order to fill each of the one hundred holes 38 and deposit the wax dots 12 onto the web 14, the drum 30 rotates within the housing 28. To rotate the drum 40, a motor (not shown) rotates a driver gear 40 in the direction of arrow B. This causes a driven gear 42 to move in the direction of arrow C which rotates the drum 30 in the direction of arrow C about the axis 44 of the drum 30. The rotational speed of the drum 30 is approximately 45 revolutions per minute.
As the drum 30 rotates about its axis 44, one of the rows of holes 38 align with the bores 34. FIG. 3 illustrates the hole 38 aligned with the bore 34 at point 46. Wax from the wax channel 26 passes through the bore 34 and into the hole 38. The rotational speed of the drum 30 allows each of the five holes 38 to completely fill with wax before they move past the bores 34. The block 36 traps the wax within the hole 38 to provide the wax dot 12 with a substantially flat portion that will readily adhere to the web 14.
Within the drum 30 beneath each row of holes 38 is a wax dot dispenser 50. The dispenser 50 is best illustrated in FIG. 4. The dispenser 50 comprises a cam follower 52, screws 54 and springs 56. Corresponding to the five holes 38, five screws 54 screw into the cam follower 52. Positioned within each hole 38 is a head 58 of each screw 54. The diameter of the head 58 is slightly less than the diameter of the hole 38 to allow the screw head 58 to move within the hole 38. Each head 58 of the screws 54 have a silicon rubber cap 60 that corresponds to the bottom of the hole 38. As illustrated in FIG. 4, the cap 60 covers the screw head 58 to prevent the wax from entering and sticking to the socket of the screw head 58. The cap 60 provides a non-stick surface for the wax dot 12 allowing the wax dot 12 to be easily deposited onto the web 14.
The dispenser 50 has five springs 56 positioned within five wells 62 in the drum 30 located on the opposite side of the cam follower 52 as the screws 54. The ends of the springs 56 extending from the wells 62 abut the cam follower 52. The cam follower 52 has bolts 64 connected at either end forming heads 66 that rest within a cam 68 in the housing 28. FIG. 5 illustrates the cam 68. The width of the cam 68 is slightly greater than the diameter of the head 66 to allow the head 66 to move along the cam 68 as the drum 30 rotates. The rotational movement of the drum 30 moves the cam follower 52 with head 66 around a follower path 70 in the housing 28. The cam 68 is nearly circular with a sudden kick-out point 76 to coordinate the dispensing of wax dots 12 from their holes 38. Following the cam 68, the cam follower 52 moves toward the axis 44 of the drum 30 to receive wax within the holes 38 at point 46 and suddenly away from the axis 44 of the drum 30 to deposit the wax dots 12 on the web 14 at the kick-out point 76. To allow motion of the cam follower 52 relative to the axis 44 of the drum 30, each cam follower 52 rests within an oval bearing 72.
FIGS. 3 and 4 illustrate the operation of the dispenser 50 of the wax dot machine 10. When each row of holes 38 align with the bores 34, the cam 68 positions the cam follower 52 against the wall 74 of the oval bearing 72 closest to the axis 44 of the drum 30. When the cam follower 52 is positioned against wall 74 of the oval bearing 72, the springs 56 compress, and the screws 56 create the hole 38 with a depth equal to the desired height of the wax dot 12. When the holes 38 align with the bores 34, the wax fills the empty space within the holes 38. As the drum 30 rotates, the cam follower 52 follows the follower path 70 provided by the cam 68. For approximately less than 90 degrees from the bores 34, the cam 68 keeps the cam follower 52 against the wall 74 of the oval bearing 72. At kick-out point 76, approximately 90 degrees from the bore 34, the cam 68 suddenly allows the compressed springs 56 to relax forcing the cam follower 52 against the wall 78 of the oval bearing 72 farthest from the axis 44. FIG. 4 illustrates a cross section of the drum 30 to illustrate the dispenser 50. At the kick-out point 76, the wax dot 12 springs toward the web 14. The expanding springs 56 at the kick-out point 76 reject the wax dot 12 from its hole 38. When the wax dot exits the wax dot former 22, the wax dot 12 contacts and adheres to the web 14. After the kick-out point 76, the cam 68 again forces the cam follower 52 against wall 74 and compresses the springs 56.
FIG. 3 illustrate one problem with the prior art wax dot machine 10. Sharp corners 80, 82 and 84 obstruct the flow of the wax within the wax channel 26. The sharp corners 80, 82 and 84 create back pressure away from the bore 34 impeding the free flow of the wax toward the holes 38. The presence of the sharp corners 80, 82 and 84 require the wax to be under considerable pressure within the wax channel 26 to provide ample flow to fill the holes 38. Additionally, the sharp corners 82 and 84 allow leakage of the wax between the housing 28 and connecting plate 32 and between the housing 28 and block 36. Because the wax within the wax channel 26 is under considerable pressure to overcome the back pressure due to the sharp corners 80, 82, and 84, the wax pushes into the spaces between the halves 25 of the housing 24, and between the housing 28, connecting plate 32 and block 36. When the wax pushes between the parts of the wax dot machine 10, the wax leaks from the wax dot machine 10.
Another problem with the wax dot machine 10 is that the block 36 is composed of steel. Because the steel block 36 is in close contact with the steel drum 30 to provide the wax dot 12 with a substantially flat portion that will readily adhere to the web 14 and to prevent wax leakage, the steel block 36 and steel drum 30 suffer wear and develop scratches from continual frictional contact with each other. Wax from the bores 34 fill these scratches and grooves on the block 36 interfering with the rotational movement of the drum 30. This problem is compounded because the wax from the wax channel 26 is under high pressure. Additionally, the scratches and grooves on the block 36 don't provide the wax dot 12 with a substantially flat portion that will readily adhere to the web 14 resulting in non-uniform size wax dots. Moreover, the drum 30 is an expensive portion of the wax dot machine 10. When scratches and groove develop on the surface, the expensive drum 30 must be replaced along with the block 36.
A further problem with the wax dot machine 10 is the screws 54. The screws 54 must be individually aligned and screwed into the cam follower 52 requiring considerable labor. Additionally, the screws 54 must be precisely aligned with threads on the cam follower 52 with little tolerance for error. If the screws 54 are not correctly aligned to the cam follower 52, the screws 54 will not completely screw into the cam follower 52. If the operator forces an incorrectly aligned screw 54, the screw 54 will be angled relative to the hole 38 allowing wax to seep past the screw head 58 and into the bearing 72. When wax leaks into the bearing 72, the sticky wax will not allow the cam follower 52 to move freely within the oval bearing 72 obstructing the kick-out of the wax dots 12. Furthermore, the wax tends to seep to the springs 56. When the wax clogs the springs 56, the wax dot machine 10 will not properly eject the wax dots 12.
Moreover, when the wax leaks into the bearings 72 and springs 56, the wax dot machine 10 must be disassembled. An operator must either clean or replace the bearings 72 and springs 56. Additionally, the operator must affix a new screw 54 to the cam follower 52. These problems with the wax dot machine 10 cause down time and operator labor expenses decreasing the efficiency and productivity of the wax dot machine 10.
Another problem with the wax dot machine 10 is that the silicon rubber cap 60 sometimes disengage from the screw head 58. Because the silicon rubber cap 60 adheres only to the top of the screw head 58 and the socket of the screw head 58, the cap 60 may lose engagement with the screw head 58 and exit the hole 38. If the cap 60 exits the hole 38, the wax filling the hole 38 will stick to the screw head 58 and fail to be deposited onto the web 14.
Another problem with the wax dot machine 10 is the sudden kick-out sometimes fail to eject the wax dot 12. When the wax dot 12 in the drum 30 has rotated to the kick-out point 76, the springs 56 may fail to force the cam follower 52 against the outer wall 78 of the bearing 72. If this happens, the wax dot 12 will not be ejected from the wax dot machine 10.
Thus, a need has arisen for an improved wax dot machine which will provide smooth flow of wax to the holes, will eliminate wax leakage into the bearings, springs and between the housing blocks and connecting block, will deposit wax dots onto the web and will provide efficient production of wax dots with minimal down time.